Energetic Basis of Microbial Growth and Persistence in Desert Ecosystems.

Microbial life is surprisingly abundant and diverse in global desert ecosystems. In these environments, microorganisms endure a multitude of physicochemical stresses, including low water potential, carbon and nitrogen starvation, and extreme temperatures. In this review, we summarize our current understanding of the energetic mechanisms and trophic dynamics that underpin microbial function in desert ecosystems. Accumulating evidence suggests that dormancy is a common strategy that facilitates microbial survival in response to water and carbon limitation. Whereas photoautotrophs are restricted to specific niches in extreme deserts, metabolically versatile heterotrophs persist even in the hyper-arid topsoils of the Atacama Desert and Antarctica. At least three distinct strategies appear to allow such microorganisms to conserve energy in these oligotrophic environments: degradation of organic energy reserves, rhodopsin- and bacteriochlorophyll-dependent light harvesting, and oxidation of the atmospheric trace gases hydrogen and carbon monoxide. In turn, these principles are relevant for understanding the composition, functionality, and resilience of desert ecosystems, as well as predicting responses to the growing problem of desertification.
Competing Interests: Conflict of Interest Disclosures for the Authors: Pok Man Leung has nothing to disclose. Sean K. Bay has nothing to disclose. Dimitri V. Meier has nothing to disclose. Eleonora Chiri has nothing to disclose. Don A. Cowan has nothing to disclose. Osnat Gillor has nothing to disclose. Dagmar Woebken has nothing to disclose. Chris Greening has nothing to disclose. Conflict of Interest Disclosures for the Editor: James C. Stegen has nothing to disclose.
(Copyright © 2020 Leung et al.)